Harmothoe globifera ( G.O. Sars, 1873 )

Barnich, Ruth & Fiege, Dieter, 2010, On the distinction of Harmothoe globifera (G. O. Sars, 1873) and some other easily confused polynoids in the NE Atlantic, with the description of a new species of Acanthicolepis Norman in McIntosh, 1900 (Polychaeta, Polynoidae), Zootaxa 2525, pp. 1-18 : 2-4

Harmothoe globifera ( G.O. Sars, 1873)

( Fig. 1 A–J)

Nychia globifera G.O. Sars, 1873: 95 .

Polynoe globifera: Hansen (1882) : 4, 14, 17, 18, 23, pl. 2 figs. 1–9. Lepidonotus globifera: Bidenkap (1894) : 61.

Eunoe globifera: Fauvel (1914) : 52; Uschakov (1982): 178.

Harmothoe globifera: Ditlevsen (1917) : 9; Loshamn (1980, unpubl. thesis): 147, fig. 72. Gattyana globifera: Augener (1929) : 693 [part].

Harmothoe nodosa: Augener (1913) : 210 [part, not Eunoe nodosa ( M. Sars, 1861) ]. Eunoe nodosa: Barnich & Fiege (2009) : 71 [not Eunoe nodosa ( M. Sars, 1861) ]. Polynoe assimilis Hansen, 1880: 225 , pl. 2 figs. 1–5; Hansen (1882): 27. Dasylepis equitis McIntosh, 1885: 77 , pl. 32 fig. 7, pl. 32A figs. 1, 2 [new synonymy]. Acanthicolepis equitis: Barnich et al. (2000) : 316 [as doubtful species].

Type material. Nychia globifera : syntypes lost; NE Atlantic, off "Storeggen" in great depths and at Lofoten Islands in 300 to 400 fathoms.

Polynoe assimilis : 4 syntypes (2 cs, 2 af, 1 mf, 1pf, several elytra free in vial), ZMBN 1989, Arctic Ocean, Norske Nordhavsexpedition 1878, St. 363, 80 °3'N 8°28'E, bluish clay, 475 m.

Dasylepis equitis : holotype (pf) lost; NE Atlantic, "Knight Errant" St. 8, Faroe Channel, 17 August 1880, 540 fathoms, ooze.

Additional material. 1 spm. (cs), Akvaplan-Niva collection, NE Atlantic, Hydro St. 3-3, 13 June 2003, 72 °33.677’N 21°1.19’E, 383 m. 1 spm. (juv.), SMF 18881, NE Atlantic, Nucula St. 5-3, 6 September 2006, 71.545°N 25.24°E, 292 m, ded. A. Sikorski. 1 spm., SMF 18882, NE Atlantic, Snøhvit St. N3-2, 19 June 2007, 71.490°N 21.087°E, 322 m, ded. A. Sikorski. 1 spm. (juv.), SMF 18883, NE Atlantic, Snøhvit St. N3-3, 19 June 2007, 71.490°N 21.087°E, 322 m, ded. A. Sikorski. 2 spms. (juv.), SMF 18884, NE Atlantic, Snøhvit St. N4-1, 19 June 2007, 71.491°N 21.091°E, 322 m, ded. A. Sikorski. 1 spm. (1 af, 1 mf, juv.), SMF 18885, NE Atlantic, Snøhvit St. N4-3, 19 June 2007, 71.491°N 21.091°E, 322 m, ded. A. Sikorski. 1 spm. (cs), SMF 18886, NE Atlantic, Snøhvit St. SD4-5, 12 June 2003, 71 °35.658’N 21°17.210’E, 343 m, ded. A. Sikorski. 1 spm. (cs), SMF 18887, NE Atlantic, Tornerose St. T 6-4, 3 June 2006, 71.586°N 22.85°E, 412 m, ded. A. Sikorski. 2 spms (2 af, 2 mf), SMF 18888, NE Atlantic, Tornerose II St. 2-4, 3 October 2006, 71.588°N 22.86°E, 412 m, ded. A. Sikorski. 1 spm. (af, juv.), SMF 18889, NE Atlantic, Tornerose II St. 3-2, 3 October 2006, 71.589°N 22.87°E, 410 m, ded. A. Sikorski. 1 spm. (juv.), SMF 18890, NE Atlantic, Tornerose II St. 5- 4, 4 October 2006, 71.585°N 22.86°E, 410 m, ded. A. Sikorski. 1 spm. (af, mf), SMF 18891, NE Atlantic, Tornerose II St. 6-4, 3 October 2006, 71.586°N 22.85°E, 412 m, ded. A. Sikorski. 2 spms. (juv.), SMF 18892, NE Atlantic, Tornerose II St. 7-1, 3 October 2006, 71.586°N 22.85°E, 412 m, ded. A. Sikorski. 1 spm. (juv., 1 af, 1 mf), SMF 18893, NE Atlantic, Tornerose II St. 8-1, 4 October 2006, 71.586°N 22.86°E, 410 m, ded. A. Sikorski. 1 spm. (cs, juv.), SMF 18894, NE Atlantic, Tornerose II St. 9-5, 3 October 2006, 71.589°N 22.85°E, 411 m, ded. A. Sikorski.

Diagnosis. Anterior pair of eyes dorsolateral at widest part of prostomium. Antennae and cirri densely papillate. Elytra densely papillate at outer lateral margin, posterior margin with scattered, short papillae; micro- and macrotubercles globose to club-shaped, covered by numerous nodular papillae, microtubercles getting larger towards outer lateral and posterior margin, macrotubercles few, in a row near posterior margin.

Description (based on specimen in good condition, SMF 18887; type material lost). Body with 36 segments. At anterior end ( Fig. 1 A), prostomium bilobed, with distinct cephalic peaks; ceratophore of median antenna in anterior notch, lateral antennae inserted ventrally, styles of antennae densely papillate, tapering; anterior pair of eyes situated dorsolaterally at widest part of prostomium, posterior pair dorsally near hind margin of prostomium; palps papillate, tapering.

Tentaculophores inserted laterally to prostomium, each with two to three notochaetae and a dorsal and ventral tentacular cirrus, styles of cirri densely papillate, tapering. Second segment with first pair of elytra, biramous parapodia, and long buccal cirri. Following segments with short, tapering, papillate ventral cirri.

Fifteen pairs of elytra, covering dorsum, on segments 2, 4, 5, 7, then on every second segment to 23, 26, 29, 32; last four segments cirrigerous; elytra densely papillate at outer lateral margin, posterior margin with scattered, short papillae; micro- and macrotubercles globose to club-shaped, covered by numerous nodular papillae, microtubercles getting larger towards outer lateral and posterior margin, macrotubercles few, in a row near posterior margin; in anterior elytra occasionally one or two branched microtubercles present near outer lateral margin. ( Fig. 1 B,C). Cirrigerous segments with distinct dorsal tubercles; dorsal cirri with cylindrical cirrophore, style densely papillate, tapering.

Parapodia biramous; notopodia with elongate acicular lobe; neuropodia with elongate prechaetal acicular lobe with digitiform supra-acicular process; neuropodial postchaetal lobe shorter than prechaetal lobe, rounded; tips of noto- and neuroacicula penetrating epidermis ( Fig. 1 D). Notochaetae stouter than neurochaetae, with distinct rows of spines and blunt tip ( Fig. 1 E); neurochaetae with distinct rows of spines, tips mainly unidentate, some upper neurochaetae minutely bidentate with fragile secondary tooth (often abraded) ( Fig. 1 F–J).

Measurements. Specimen SMF 18887: cs in two fragments, L 22 mm, W 5 mm for 36 segments ( Fig. 1 A–J).

Remarks. Although the syntypes of Nychia globifera are lost, G.O. Sars' (1873) description is rather detailed, especially regarding the densely papillate dorsal cirri and elytral margin, and the elytral tubercles covered by nodular papillae. These characters, which have been first figured by Hansen (1882), are very typical and allow the certain identification of the species.

G.O. Sars (1873) originally assigned the species to Nychia Malmgren, 1866 (name pre-occupied, today Gattyana McIntosh, 1897 ). It was later considered as Polynoe Savigny in Lamarck, 1818 by Hansen (1880, 1882), and as Lepidonotus Leach, 1816 by Bidenkap (1894). Augener (1913) put the species in synonymy with Harmothoe nodosa ( M. Sars, 1861) together with Polynoe assimilis Hansen, 1880 , Eunoe oerstedi Malmgren, 1866 and some other species, but without discussing this decision. Fauvel (1914) however considered globifera valid, and was the first to discuss the generic placement. He put the species in Eunoe Malmgren, 1866 because of the unidentate neurochaetae and exclusively stout notochaetae (in contrast to Gattyana which has two kinds of notochaetae: stout with blunt and slender with capillary tip; see also Barnich & Fiege 2009). Ditlevsen (1917) finally checked the types of Polynoe assimilis and confirmed the synonymy with globifera , but he moved the species to Harmothoe . The validity of globifera and its synonymy with assimilis was finally accepted by Augener (1929), but he still considered the species to belong to Gattyana . In his unpublished thesis Loshamn (1980) finally placed it within Harmothoe .

The main reason for this disagreement in the literature is the shape of the tip in the neurochaetae. G.O. Sars describes them as being all unidentate; Loshamn however mentions some upper neurochaetae being minutely bidentate, a fact which we found confirmed in the recently examined specimens listed above. Since the secondary tooth is often abraded, the bidentate neurochaetae are easily overlooked, and thus the species could be mistaken for a Eunoe (see Augener 1913, Fauvel 1914, Barnich & Fiege 2009). But our examination of several young and adult specimens showed, that a few bidentate neurochaetae are always present and even when abraded, this tip is different from a unidentate tip (see Fig. 1 G–J). Therefore, we finally confirm Loshamn's opinion and place the species within Harmothoe and not within Eunoe . The most striking characters of Harmothoe globifera are found in the elytra with a densely papillate outer lateral margin, micro- and macrotubercles covered by nodular papillae, and in the densely papillate antennae and cirri ( Fig. 1 A–C). At first glance, the species could be confused with Eunoe nodosa ( M. Sars, 1861) , which has also nodular macrotubercles. But, E. nodosa differs by the exclusively unidentate neurochaetae, the less densely papillate elytral margin, antennae and cirri, the microtubercles which are mostly low semiglobose and distally nodular, and the macrotubercles with nodular papillae only distally ( Fig. 2 A–K; see description below).

Harmothoe globifera could also be confused with H. clavigera ( M. Sars, 1863) which was redescribed by Barnich & Fiege (2009). In H. clavigera , however, the neurochaetae are mainly bidentate, elytral microtubercles are conical, and macrotubercles are rather large, club-shaped with nodular papillae only distally.

Dasylepis equitis is only known from a posterior fragment described by McIntosh (1885); this fragment seems to be lost, since the vial labelled " Dasylepis equitis , holotype, BMNH 1885.12.1.57" contains two opheliids. Unfortunately, McIntosh did not explain why he assigned his species to Dasylepis Malmgren, 1867 (name pre-occupied, replaced by Acanthicolepis Norman in McIntosh, 1900). Already in our revision of Acanthicolepis ( Barnich et al. 2000) , we considered Dasylepis equitis a doubtful species, close to Nychia globifera . Having now examined a number of specimens of H. globifera and compared them to McIntosh's description of the dorsal cirri and elytra, we finally confirm the synonymy of D. equitis with H. globifera .

Distribution and habitat. Arctic Ocean and Northeast Atlantic; on mud and clay, in 250 to 3400 m depth (see also Ditlevsen 1917).

Figures

FIGURE 1. Harmothoe globifera (SMF 18887). (A) anterior end; (B) right anterior elytron from unknown segment, free in vial; (C) micro- and macrotubercles from same; (D) left elytragerous parapodium from segment 5, posterior view; (E) distal half of long notochaeta; (F) distal part of middle, unidentate neurochaeta; (G) tip of same; (H) tip of upper bidentate neurochaeta with fragile secondary tooth; (I) tip of upper bidentate neurochaeta with abraded secondary tooth; (J) tip of lower unidentate neurochaeta. (Scales: A, B = 2 mm; C = 250 µm; D = 500 µm; E, F = 100 µm; G – J = 50 µm).

FIGURE 2. Eunoe nodosa (ZMO C 5244). (A) anterior end, styles of median antenna, left tentacular and right dorsal tentacular cirri, and dorsal cirri missing; (B) right anterior elytron from unknown segment, free in vial; (C) micro- and macrotubercles at posterior margin from same; (D) micro-and macrotubercles at outer lateral margin from same; (E) right elytragerous parapodium from segment 21, posterior view; (F) distal half of long notochaeta; (G) tip of same; (H) distal part of middle neurochaeta; (I) tip of same; (J) tip of upper neurochaeta; (K) tip of lower neurochaeta. (Scales: A, B = 2 mm; C, D, F, H = 250 µm; E = 500 µm; G, I – K = 100 µm).